SUMMARY: Project 4 ? Sources of Airborne PCBs Project 4 addresses SRP mandates for improved methods for detecting and assessing the hazards of Superfund chemicals. We will identify and characterize sources of airborne polychlorinated biphenyls (PCBs) within schools and homes, and near superfund sites with PCB-contaminated sediments. Sources of airborne PCBs may include building materials contaminated with legacy Aroclor PCBs, as well as consumer products that are inadvertently contaminated with PCBs through the manufacturing process. Our central hypothesis is that emissions of airborne PCBs are a function of the properties of the PCB congeners, environmental variables, and exposed surfaces in which the PCBs reside. We will examine all PCB congeners, and both Aroclor and non-Aroclor sources of airborne PCBs. We will evaluate emissions from materials and products found in schools and neighborhoods in our partner communities using methods that are accurate, precise, and reproducible. Data produced by Project 4 will enable cost-effective decisions for their removal. We will address Project 4?s central hypothesis by pursuing the following Specific Aims: Aim 1: We will develop novel passive sampling materials. We will design and manufacture tailored electrospun nanofiber mat (ENM) as an efficient and adaptable material for passive air sampling. We will design, calibrate, and deploy samplers equipped with this novel material to detect and measure PCB congeners in the environment. Aim 2: We will identify specific sources of airborne PCBs in schools and homes. ISRP research has already shown that building materials contaminated with Aroclors, and consumer products contaminated with non-Aroclor congeners, can contribute to high levels of PCBs in indoor air. We will measure airborne PCBs in schools and homes of Columbus Junction and West Liberty, Iowa; generate an inventory of potential sources in the school rooms; and measure emissions from those materials. We will also develop new laboratory methods to measure emissions and will apply computational fluid dynamics modeling of school rooms to determine the role of each material or consumer product as a source of airborne PCBs. Aim 3: We will characterize emissions from contaminated waters nation-wide. We hypothesize that contaminated waters are a major outdoor source of airborne PCB exposure nation-wide. We will use existing public data to predict emissions, dispersion, and annual median air concentrations in communities surrounding these waters. We will test our prediction through local measurements of airborne PCBs and communicate our findings to local communities and environmental protection officials, including the EPA. Our studies require close collaboration with the ISRP Analytical Core, Community Engagement Core, and Data Management and Analysis Core. Through these collaborations, Project 4 will provide strategies to prioritize technically and economically practical remediation options that focus on reduction of exposure to PCBs.